Dissemination Area Boundary File
Dissemination Areas (DAs) are the smallest geographic areas for which census data are made available by Statistics Canada. The DA is the geographic area canvassed by one census representative, the boundaries follow recognizable physical features such as streets / roads, lakes / rivers and administrative limits. The areas are composed of one or more neighbouring blocks, with a population of 400 to 700 persons. All / 100% of Canada is divided into an assortment of dissemination areas. The dissemination area (DA) is a small, relatively stable geographic unit composed / aggregate of one or more block/s. It is the smallest standard geographic area for which all census data are disseminated. The United States equivalent is a Block Group. The Dissemination Area is the new defacto / standard geographic area fo collecting census demographic data. Dissemination Areas replaced Enumeration Areas (EA) in 2001, as a basic unit for dissemination. DAs respect several delineation criteria designed to maximize their usefulness for data analyses, examples include the following:
- DA boundaries respect the boundaries of census subdivisions and census tracts. DAs therefore remain stable over time, to the extent that census subdivisions and census tracts do.
- DAs are uniform in terms of population size, which is targeted from 400 to 700 persons to avoid data suppression. DAs with lower population counts (including zero population) may result in order to respect the boundaries of census subdivisions and census tracts. DAs with higher population counts may also result.
- DA boundaries follow roads and other major features (such as railways, water features, power transmission lines), where these features form part of the boundaries of census subdivisions or census tracts.
- DA within a DA is formed when the population of apartment or townhouse complexes meets or exceeds 300 persons.
- DAs are compact in shape, to the extent possible while respecting the above criteria.
- Operational requirements limit to 99 the number of blocks that can be included in a DA.
In order to meet the operational constraint of releasing population and dwelling counts in the spring following the census year, the population counts used to delineate DAs are taken from the previous census. To delineate DAs for 2006, sufficiently accurate block population counts based on 2001 Census data. Each Dissemination Area is assigned a four-digit code that is unique within a Census Division (CD), as well tagged with a 2-Digit Province or Territory Code. In order to identify each DA uniquely in Canada, the two-digit province code and the 2-digit CD code must precede the 4-Digit DA code. The dataset contains the concatenation of the 2 Codes.
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